From Basement 2 to 2nd Floor of Internetwork Business

Decibel (dB) and dB relative to a milliwatt (dBm) represent two different but related concepts.

A dB is a shorthand way to express the ratio of two values. As a unit for the strength of a signal, dB expresses the ratio between two power levels. To be exact, dB = log (P1/P2).

Using the decibel allows us to contrast greatly differing power levels (a common predicament in radio link design) with a simple two- or three-digit number instead of a more burdensome nine- or 10-digit one.

For instance, instead of characterizing the difference in two power levels as 1,000,000,000 to 1, it’s much simpler to use the decibel representation as 10*log (1,000,000,000/1), or 90 dB. The same goes for very small numbers: The ratio of 0.000000001 to 1 can be characterized as -90 dB. This makes keeping track of signal levels much simpler.

The unit dBm denotes an absolute power level measured in decibels and referenced to 1 milliwatt (mW). To convert from absolute power “P” (in watts) to dBm, use the formula dBm = 10*log (P/1 mW). This equation looks almost the same as that for the dB. However, now the power level “P” has been referenced to 1 mW. It turns out that in the practical radio world, 1 mW is a convenient reference point from which to measure power.

Use dB when expressing the ratio between two power values. Use dBm when expressing an absolute value of power.

The risk to operations is significant with the loss of a qualified IT expert. The remaining staff must compensate to avoid disruptions that impact customer satisfaction, reduce productivity or inflict economic loss.

Return on investment in an employee is disrupted with turnover. Employers invest in certified staff through training courses, books and technical materials, practice equipment, time off for study and exams, and the cost of the exam itself.

It takes time to achieve certification. The typical CCIE will spend at least 18 months completing the process and take the lab exam more than once before passing.

The benefits of Gold or Silver Channel Partner status are only available to companies who maintain the required number of certified staff.

Cisco introduced CCIE in 1993 to help individuals, companies, industries and countries succeed in the networked world, by distinguishing the top echelon of internetworking experts.

Today the CCIE program sets the standard for internetworking expertise and evolves with the industry. The CCIE program is committed to valid, fair and high quality exams.

What CCIE certification stands for:

CCIE identifies experts with the skills and experience to handle the most challenging assignments in their field. CCIE exams are constantly updated and revised to evolve with the industry, focusing on current technologies and real-world applications.

CCIE is recognized worldwide as the most respected high-level certification in the industry (see Awards & Recognitions). The program continually updates and revises its testing tools and methodologies to ensure unparalleled program quality, relevance and value.

CCIE is an objective way to compare individuals, or job candidates, with different experience and backgrounds.

Preferred status is given to Cisco partners who employ CCIEs (find out more at Cisco Channel Programs).

Why you should hire a CCIE:

Maintenance of your network is fundamental to protect assets and to ensure seamless operations. The environment is growing more complex with operations conducted over VPNs, wireless, remote access and the Internet. You need proven experts to choose, implement and maintain the solutions required.

Having certified staff can increase the confidence of your customers, investors and business partners, and thereby boost your organization’s credibility, reputation and value.

Certified CCIEs are a highly-select group. Less than 3% of all Cisco certified individuals make it to the CCIE level, a tiny fraction of IT professionals worldwide.

Passing the exams is not easy. Earning your CCIE requires passing a lab exam in a time pressured environment. Hands-on experience is the only way to prepare for the lab.

CCIEs have invested a lot to expand their knowledge and further their careers. The average candidate spends thousands of their own dollars and at least 18 months pursuing certification. He or she will attempt the lab exam more than once before passing.

CCIEs are committed to maintaining their expert skills. Keeping their status active requires passing a recertification exam every two years.

Why you don’t want to lose a CCIE from your staff:

The risk to operations is significant with the loss of a qualified IT expert. The remaining staff must compensate to avoid disruptions that impact customer satisfaction, reduce productivity or inflict economic loss.

Return on investment in an employee is disrupted with turnover. Employers invest in certified staff through training courses, books and technical materials, practice equipment, time off for study and exams, and the cost of the exam itself.

It takes time to achieve certification. The typical CCIE will spend at least 18 months completing the process and take the lab exam more than once before passing.

The benefits of Gold or Silver Channel Partner status are only available to companies who maintain the required number of certified staff.

IPv6 multicast renames IGMP to the Multicast Listener Discovery Protocol (MLP). Version 1 of MLD is similar to IGMP Version 2, while Version 2 of MLD is similar to Version 3 IGMP. As such, MLD Version 2 Source Specific Multicast (SSM) for IPv6 environments.

Using MLD, hosts can indicate they want to receive multicast transmissions for select groups. Routers (queriers) can control the flow of multicast in the network through the use of MLD.

MLD uses the Internet Control Message Protocol (ICMP) to carry its messages. All such messages are link-local in scope, and they all have the router alert option set.

MLD uses three types of messages – Query, Report, and Done. The Done message is like the Leave message in IGMP version 2. It indicates a host no longer wants to receive the multicast transmission. This triggers a Query to check for any more receivers on the segment.

Configuration options for MLD will be very similar to configuration tasks we needed to master for IGMP. You can limit the number of receivers with the ipv6 mld limit command. If you want the interface to “permanently” subscribe, you can use the ipv6 mld join-group command. Also, like in IGMP, there are several timers you may manipulate for the protocol’s mechanics.

Configuring IPv6 multicast-routing with the global configuration command ipv6 multicast-routing, automatically configures Protocol Independent Multicast (PIM) an all active interfaces. This also includes the automatic configuration of MLD. Here are verifications:

Notice the PIM is indeed enabled on the Fa0/0 we have configured in this scenario. Now for the verification of MLD:

R0#show ipv6 mld interface
Tunnel0 is up, line protocol is up
Internet address is FE80::C000:2FF:FE97:0/10
MLD is disabled on interface
VoIP-Null0 is up, line protocol is up
Internet address is ::/0
MLD is disabled on interface
FastEthernet0/0 is up, line protocol is up
Internet address is FE80::C000:2FF:FE97:0/10
MLD is enabled on interface Current MLD version is 2
MLD query interval is 125 seconds
MLD querier timeout is 255 seconds
MLD max query response time is 10 seconds
Last member query response interval is 1 seconds
MLD activity: 5 joins, 0 leaves
MLD querying router is FE80::C000:2FF:FE97:0 (this system)
FastEthernet0/1 is administratively down, line protocol is down
Internet address is ::/0
MLD is disabled on interface

Our CCIE Data Center version 2.0 Rack Rental system is now in beta testing phase. Click here to submit a request for beta access and I will contact you directly with more details on timing and availability. Our CCIE DCv2 Rack Rentals consist of the following: Nexus 9300 ACI Spines Nexus 9300 ACI Leafs Application [...]

Now that Cisco Live US 2016 is winding down, we’re going full steam ahead with our CCIE Data Center version 2.0 Blueprint updates. For those of you that haven’t seen it, my live blog of the CCIE DCv2 Techtorial @ Cisco Live US 2016 can help to answer some additional questions about the exam content [...]

This morning I’m in Las Vegas for Cisco Live 2016, and am attending TECCCIE-3644 – CCIE DC Techtorial which focuses on the new CCIE Data Center v2 updates. I’m live blogging the session so please feel free to submit your questions for the CCIE team as a comment here and I’ll try to get an answer for [...]

Finally, Cisco has made the official announcement on the upcoming changes for CCIE Security Version 5. Both the written exam and the lab exam will be changes go live starting 31st of January 2017, which gives you the usual 6 months window to pass the Version 4 exam, before the change to Version 5 occurs. [...]

Congratulations to Neil Moore on passing the CCDE Practical Exam this week, and becoming a NONTUPLE (9x) CCIE & CCDE! Neil was a student in both my CCIE Data Center Bootcamp and CCDE Bootcamp within the past few years, and is truly an inspiration to us all. Neil’s brother Kelly is also a CCIE in Data [...]